'To have a combined data base requires compatibility of the numbering system and information captured (EDI compliant). That's the real reason behind the Real ID. No doubt the driver's license number will include country code and state-province code. Even though the card stock might look different depending upon the issuing agency, the data will be designed to reside in a single database for all three countries.'
http://www.channelingreality.com/NAU/REAL_ID.htm
http://www.channelingreality.com/NAU/REAL_ID.htm